1. Field of the Invention
The present invention relates to a flexible circuit board, and more particularly to a flexible circuit board provided with a plurality of electronic circuit mounting portions and to an electronic circuit device and a mobile communication terminal each including the flexible circuit board.
2. Description of the Related Art
An electronic component, which is included in an electronic circuit device in compact electronic equipment, such as a mobile phone, a video camera, and the like, is mounted on a circuit board through soldering or the like. The circuit board is generally made of organic composite materials. The outer size of mounted components is limited by a substrate size.
In recent years, there is a tendency in that the total size of mounted components is almost equal to an outer size of an electronic equipment in response to a demand for further reduction in size of the electronic equipment. Therefore, a space for receiving mounted components is becoming extremely small.
In view of this, there provides a technique in which electronic components are mounted on flexible boards so as to be put in a limited space in an electronic equipment.
For example, as to an electronic circuit device disclosed in JP2001-358422A, a plurality of circuit boards is electrically and mechanically connected with each other through a flexible board so as to receive a plurality of electronic circuits in a limited space in a cabinet of an electronic device. Further, the circuit boards are arranged in the electronic device in an overlapping manner by folding the flexible board at a predetermined part thereof. Thus, the electronic circuits can be mounted efficiently at high density in the electronic device.
Further, in a mobile communication terminal disclosed in JP2004-064575A, two camera units are mounted on the same flexible printed board. The flexible printed board is appropriately folded so that view-field directions of both the cameras are opposite to one another. Therefore, the flexible printed board as a control printed wiring board does not need to be mounted on each camera.
Moreover, in an attachment structure of a flexible circuit board disclosed in JP 06-048321 B, the flexible circuit board and a connector housing are collectively fixed by means of a same stopper. The stopper reliably establishes fixation of an intermediate portion of the flexible circuit board. This realizes the attachment structure of the flexible circuit board with stable fixation.
Now, a flexible board sometimes has a plurality of mounting portions, each of which is mounted with an electronic circuit including electronic components and is arranged toward different directions. For example, a flexible board may have two electronic circuit mounting portions arranged in perpendicular directions through a connector mounting portion which mounts a connector. In this arrangement, manufactures mount the connector mounting portion to a connector retaining portion on an electronic circuit device, after they mount the two electronic circuit mounting portions to the electronic circuit device first, and then, the flexible board is held on the electronic circuit device by each of the retaining portions. In this case, a certain force acts on the connector mounting portion in its rotational direction from the two mounted electronic circuit mounting portions, when manufactures mount the connector mounting portion to the connector retaining portion. The flexible board bends due to this force when manufactures mount the connector mounting portion to the connector retaining portion on the electronic circuit device. They may mount the flexible board to each of the retaining portions on the electronic circuit device while the flexible board bends. This may lead to deformation of a connector terminal.
Also, in the case where they first mount the connector mounting portion on the electronic circuit device ahead of mounting the two electronic circuit mounting portions, the force is generated in a certain direction with respect to the electronic circuit mounting portion which is mounted later. This force causes excessive deformation of the electronic circuit mounting portion. This is from the fact that the electronic circuit mounting portion is fitted into a claw-shape portion of the retaining portion of the electronic circuit device at an amount exceeding a predetermined fitting amount. As a result, the mounted components may be peeled off or damaged. Here, the above certain direction depends on the positions of the connector mounting portion and the previously mounted electronic circuit mounting portion and the length of the flexible board that connects the connector mounting portion with the electronic circuit mounting potions. Further, the direction varies in accordance with the lengths and shapes of the retaining portion of the electronic circuit device, electronic circuit mounting portions, and a flexible board.
As to the above-mentioned electronic circuit device disclosed in JP 2001-358422 A, the plurality of circuit boards are parallelly arranged to be mounted on the electronic circuit device by folding the flexible board at the predetermined part. However, as described above, it is not disclosed that the plurality of circuit boards are arranged to be mounted on the electronic circuit device in different directions, for example, perpendicular directions.
Further, JP 2004-064575 A discloses that the view-field directions of the two cameras are made opposite to each other by folding the flexible printed board. However, it is not disclosed that a plurality of cameras is arranged in different directions, for example, perpendicular directions, to be mounted on a mobile communication terminal.
Furthermore, JP 06-048321 U does not disclose that a plurality of circuit boards is arranged in different directions to be mounted on an electronic circuit device.